Experts question decision to vent and burn toxic vinyl chloride from derailed tankers in East Palestine, Ohio

The experts said that the tank cars were not undergoing a chemical reaction that would have caused them to explode, calling into question the decision of first responders to vent and burn the hazardous liquified gas inside.

Experts question decision to vent and burn toxic vinyl chloride from derailed tankers in East Palestine, Ohio


The US National Transportation Safety Board (NTSB) called experts to testify at an hearing on Thursday about the February derailment of a train in East Palestine, Ohio. They said that the vinyl chloride-containing tank cars were not experiencing a chemical reaction which would have caused the explosion. This calls into question the decision made by first responders to burn and vent the dangerous chemical within.

Residents of East Palestine, who were affected by the derailment of the train, have asked for an explanation of the decision to burn the toxic vinyl chloride that was released from five derailed tanks cars. This caused a cloud of black smoke to drift ominously across the town on February 6 and south into Pennsylvania, three days after it first derailed.

Representatives from the train operator Norfolk Southern, as well as emergency response contractors hired by two of the companies to assist after the accident, testified at the NTSB's Thursday investigative field hearing that they were concerned the railcars could explode due to a variety of factors.

  • The pressure relief valves of several cars that were periodically releasing liquified gases, appeared to have stopped working. The chemical safety data sheets of vinyl chloride stated that it could cause a dangerous explosion if only exposed to heat.

Keith Drabick of the East Palestine Fire Department who led the response to the derailment site testified that Norfolk Southern, its consultants and the experts on the scene had assessed the uncertainty and determined that the only viable option was a "vent and burn". This involved placing small charges onto the railcars, blowing holes into the tanks and letting the liquid vinyl chloride drain down into pits dug in the ground.

He stated that the final decision was ultimately his.

He testified that 'the final yes' was given to him based on consensus amongst everyone in the unified commands.

Drabick stated that during a meeting he had with Gov. Mike DeWine, members of Norfolk Southern and Drabick were told by him to make a quick decision on Sunday night. This was two days after the derailment that occurred on February 3.

Drabick, during the hearing, said that he was told that if we went down to this room we would have 13 minutes to decide because of weather conditions and other factors that could come into play when daylight begins to fade.

Drabick said in written testimony to investigators released on Thursday that he was 'kind of blindsided', and this is probably the thing most bothering him out of everything.

The evidence tells a completely different story

The evidence presented on Thursday included photographs, laboratory testing, and temperature readings taken from the cars. This suggests that the railroad's experts and the railroad misinterpreted signs of a reaction.

Paul Stancil, an investigator with the NTSB, showed a graph showing temperatures taken on one of the vinyl chloride tanks that investigators were most concerned about. Temperatures taken Sunday, February 5 appeared to be decreasing rather than increasing.

Would you agree that the temperature trend was downwards or decreasing, except for the spike during the night? Stancil asked Drew McCarty, of Specialized Professional Services Inc. one of the contractors Norfolk Southern had hired to help with the response.

Why was it still a problem when the tank car's temperature was dropping? Stancil asked.

McCarty stated that he did not place much trust in the temperatures readings, as he was not confident they were accurate. He said that the workers used thermal imaging cameras to measure the temperature of the outside of the tanks. However, because of damage to the tankers' metal shells, they were not sure if they always hit it.

He said, 'We as the contractor team, and Norfolk Southern did not give much credence to those readings because we believed we could have been contacting the thermometer, thermal blanket, or insulation and may or may even have touched the tank car.

McCarty stated that the heat of the fires which raged for hours around the cars was a bigger concern.

He also said that the pressure relief vents, which are meant to release liquified gases when pressure increases, were working but then seemed to stop.

McCarty stated that'something either gummed up the machine or mechanically messed up the machine, but either way it was extremely dangerous'.

He stated that the consensus among the railroad's experts and the railroad at the time was a polymerization was taking place inside the cars. The heat generated when liquified Vinyl Chloride polymerizes, or turns quickly into solid Polyvinyl Chloride, which is the familiar white PVC pipe that many plumbing systems are made from, is immense. Experts were concerned that the reaction could explode the cars and send metal fragments flying up to one mile.

The pressure relief valves were believed to be blocked by polyvinylchloride, which had formed inside the vehicles.

The evidence presented Thursday revealed that the valves were blocked not from the inside but rather the outside. This was contrary to what first responders believed.

NTSB investigators confirmed on Thursday that the aluminum housing of some valves melted during the fire, causing them to be damaged and clogged.

OxyVinyls - a subsidiary company of Occidental Chemical, which manufactures vinyl chloride - conducted lab tests after venting and burning the cars. They found that no polyvinylchloride had been formed.

Paul Thomas, vice-president of health, environmental, safety, and security at OxyVinyls said that at the hearing, the company had convened a group of safety experts as soon as it learned about the derailment. The team continued to communicate with Norfolk Southern, its contractors, and other parties by phone up until Sunday, just two days after this crash.

Thomas stated that they tried to communicate in two conference calls that, based on their evidence, they did not believe an explosive polymerization was taking place.

The reaction would cause a temperature increase that would last throughout the duration. Thomas stated in his opening remarks that we stressed to Norfolk Southern and their contractors the importance of monitoring rail car temperatures.

He testified that based on the temperature readings 'we tried to communicate' we didn't think polymerization had occurred.

Thomas, however, said that OxyVinyls wasn't present at the meetings when the decision to burn and vent the cars was made. It was instead instructed to have its experts communicate through a contractor, who would then relay information to Norfolk Southern.

Robert Wood, the incident commander at Norfolk Southern, testified in court that the company relied also on the information contained in OxyVinyl’s material safety data sheets for vinyl chloride when making the decision to vent the cars and burn them. This sheet warns people who work with vinyl chloride not to expose it to extreme heat as this could lead explosive polymerization.

William Carroll, an independent expert from the University of Indiana, testified that he found the term "explosive polymerization" confusing. He said that 'that made no sense', based on years of experience with Vinyl Chloride.

He traced it back to two scientific papers from 1970 that are no more in print. He said that references to these articles state that vinyl chloride polymerizes in the presence oxygen.

OxyVinyls, however, testified that it had stabilised the vinyl chloride chemical before shipping by removing the oxygen from the tanks to the point where there was almost no oxygen present.

Carroll stated that the chemical would not have polymerized without oxygen or an initiator.

He said that vinyl chloride does not polymerize solely on heat. It doesn't spontaneously polymerize.

Drabick said that if he knew that OxyVinyls didn't believe that vinyl chloride was experiencing an explosive reaction, he might not have been able to change the outcome of vent and burn. He said that there were no other options for removing the vinyl chloride from damaged tankers.

McCarty said that first responders were considering a "hot tap," in which they would cut holes in the tanks with a welding tool and then pump vinyl chloride into a second container.

The team, however, decided it was not worth the risk because they did not know how much liquid vinyl chloride was still in the vehicles. A hot torch could have caused a car explosion if there was no liquid in the tanks.

McCarty stated that he made the decision to ensure safety for his community as well as for himself and his people.